The present disclosure relates to coding/decoding systems for multi-directional imaging system and, in particular, to use of coding techniques that originally were developed for flat images, for multi-directional image data.
In multi-directional imaging, a two-dimensional image represents image content taken from multiple fields of view. Omnidirectional imaging is one type of multi-directional imaging where a single image represents content viewable from a single vantage point in all directions—360° horizontally about the vantage point and 360° vertically about the vantage point. Other multi-directional images may capture data in fields of view that are not fully 360°.
Modern coding protocols tend to be inefficient when coding multi-directional images. Multi-directional images tend to allocate real estate within the images to the different fields of view essentially in a fixed manner. For example, in many multi-directional imaging formats, different fields of view may be allocated space in the multi-directional image equally. Some other multi-directional imaging formats allocate space unequally but in a fixed manner. And, many applications that consume multi-directional imaging tend to use only a portion of the multi-directional image during rendering, which causes resources spent to code un-used portions of the multi-directional image to be wasted.
Accordingly, the inventors recognized a need to improve coding systems to increase efficiency of multi-directional image data.